Excessive engine vibration Yanmar 3GM30f

[Rigger]

I have a yanmar 3GM30F. I’m getting severe engine vibration when going forward , I can’t go above 1000rpm withoit the engine shaking itself apart. There is no problem in neutral or when going astern. An engineer has looked at the gearbox and said there were just some loose bolts on the drive plate. The problem persists and is now worse than ever. Any ideas as to cause ?

 

[vyv_cox]

Are the engine mounts all sound and carrying similar loads each side? Also check the bolts attaching the mounts to the engine block.

This assuming you have already checked alignment and coupling.

 

[Just_sayin']

Propeller problem?

 

[Rigger]

Thanks for replies.
I have recently changed the prop. I had a folding prop which malfunctioned and have replaced it with the original fixed prop.
If it’s the engine mounts (which I have to admit are pretty old!) would you expect the problem only to happen when going forward?

 

[Graham376]

Thanks for replies.
I have recently changed the prop. I had a folding prop which malfunctioned and have replaced it with the original fixed prop.
If it’s the engine mounts (which I have to admit are pretty old!) would you expect the problem only to happen when going forward?

Have you by any chance moved a rope cutter too far forward on the shaft?

 

[Rigger]

Have you by any chance moved a rope cutter too far forward on the shaft?

Not that I’m aware of. I do have a rope cutter but I reinstalled it in the same place as previous